Looking for cheap lunch recipes to mix it up a bit.

I used to eat microwavable meals because they're easy, but they come in around $3 per meal and I realized that I could eat lunch for a dollar or less a meal, so I've been making stuff right now.

Currently my rotation includes a vegetable soup, ground beef with beef gravy and egg noodles, and a simple PB&J.

What do you take for lunch that's cheap and tasty? (I have access to a microwave at work, so reheatable meals are cool.)